Absorbent articles such as sanitary napkins, adult incontinence articles, diapers and pantiliners are often manufactured and/or packaged on a high speed production line where individual articles may move along a production path at a speed of hundreds of meters per minute, for example higher than 200 m/min, and manufacturers of articles are continually trying to increase manufacturing speed.
During the manufacturing and/or packaging process, the absorbent article may undergo a folding process. One of ways to fold absorbent articles is a trifolding process by which an absorbent article is folded into three parts. A trifolding process may comprise folding absorbent articles about two fold lines which are transversal to their longitudinal axis, into three parts, respectively forming a leading portion, a central portion and a trailing portion of the article in a machine direction. In a trifolding process, an article may be first folded in around two thirds in the longitudinal direction by folding either the front portion or the rear portion, and second folded in around one third by folding the remaining rear portion or front portion. It is preferable that tri-folded pads has a consistent length among all the pads with minimum variation. However, current manufacturing practices often do not provide stable tri-folded product length for downstream pouch folding and packaging process, resulting in products that may have undesirable characteristics in the market place.
In a folding process providing a tri-folded article disclosed in Japanese laid-open patent publication No. 2002-18664, the folding process includes steps folding a trailing end portion first and then folding a leading end portion later. This type of process needs spacing between articles prior to first folding which requires accelerating moving speed of an article before the first folding. In addition, after tri-folding process, tri-folded product spacing needs to be reduced before moving into pouch folding process, which requires decelerating moving speed of an article. Such speed change tends to create increased article length variation which results in a wide variation in a tri-folded, article length which gets more conspicuous when process speed get faster.
In another folding process providing a tri-folded article disclosed in Japanese laid-open patent publication No. 2003/267468, the folding process includes steps of first folding a leading end portion, then turning the first folded article about 180 degree, and second folding a tailing end portion. This type of process may require a wide pad transition distance and product transition direction change between the first and the second folding steps which tends to increase article length variation. Product transition direction change between the first and second folding steps tends to increase article lenght variation. Japanese laid-open patent publication No. 2003/267468 discloses a folding equipment comprising a downward facing U-shape transport belt wrap around a guide drum which changes a moving direction of the first folded article about 180 degree.
Accordingly, there is a need for a process and a system for folding articles reducing tri-folded article length variation especially in high production speed.
In addition, there is a need for a process and a system for folding articles with minimizing an article transition distance and direction change between the first and second folding steps.